1. Technical Field
The present invention relates to semiconductor packaging structures. More particularly, the present invention relates to a manufacturing method for molding image sensor package structure and an image sensor package structure made through the method.
2. Description of Related Art
Conventionally, an image sensor package is made by placing an image sensor chip on a substrate, connecting the image sensor chip and the substrate by means of metal conducting wires, and mounting a transparent lid (e.g. glass) upon the image sensor chip so as to allow light to pass through the transparent lid and get acquired by the sensor chip. The resultant image sensor package is for a system manufacturer to integrate to an external device, such as a printed circuit board, or to apply to any of various electronic products such as a DSC (Digital Still Camera), a DV (Digital Video), a security monitoring system, a mobile phone, or a vehicle image sensing module.
In traditional image sensor package, the transparent lid is adhered beforehand to the image sensor chip for protecting the chip against foreign pollutant particles. After the transparent lid is installed, the metal conducting wires are arranged so as to electrically connect the image sensor chip with the substrate or a carrier. Then, a macromolecular liquid compound is used to cover the metal conducting wires. However, the macromolecular liquid compound is quite costly and needs to be arranged through a time-consuming dispensing process. Consequently, the traditional technology of such image sensor package is disadvantageous in its prolonged processing cycle and high cost.
In addressing the above problems, U.S. Pat. No. 7,312,106 has proposed a method for encapsulating a chip having a sensitive surface. The known method comprises mounting a chip having a sensitive chip surface and contact pads on a carrier having carrier contact pads; bonding the chip contact pads to the carrier contact pads; applying a closed dam around the sensitive chip surface, which defines an open space inside the dam; positioning a lid, which closes the open space inside the dam; positioning the chip and the carrier into a mould; introducing package material into the mould for transfer molding; and conducting a post mold cure process so as to complete encapsulation of the chip.
The upper half of the mould could have an inward-extending section facing the sensitive chip surface so as to facilitate the package material in fully covering around the lid without covering the central upper surface of the lid, thereby protecting the periphery of the lid. However, the inward-extending section could significantly increase the cost for making the upper mould half, and is unfavorable to the purpose of reducing the overall cost of the image sensor package. Although the prior art method might also be accomplished by using a different upper mould half without the inward-extending section, it otherwise requires an additional elastic material settled between the upper mould half and the lid so as to protect the lid from the pressure exerted by the direct application of the upper mould. Even when the elastic material is used, the known method for encapsulating a chip still puts the image sensor in risk from damage, thus leading to a decreased yield rate.